package com.kfm.base.map;


import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

public class Demo03<T, X> {

    public static void main(String[] args) {
        Collection<Integer> c = List.of(1, 2);

        // ? extends Object  Object 及其子类
        List<Object> list = new ArrayList<>(c);

        list.add("String");

//        String s = list.get(0);

        // ? super String  String 及其父类


        //
        List<List> list2 = new ArrayList<>();


        List[] list3 = new List[3];

        list3[0] = list;

    }


    public void test(List<String> t){
    }

}
